Ordinary fixed telephone systems have remote waking-up and state detection capability, i.e., the central office equipment can remote wake up terminal units and detect the state of terminal units through twisted pair lines.
FIG. 1 shows a block diagram of the subscriber network interface part of an ordinary telephone system, comprising a central office interface equipment 1, a telephone set 2, and twisted pair lines 3 that connect the central office interface equipment 1 and telephone set 2, wherein, the central office interface equipment 1 further comprises a voice receiving/transmitting module 11, a power supply and monitoring module 12, a ringing generator module 13, and transformers 14 and 15; the telephone set comprises a voice processing module 21, a regulated power supply module 22, a ringing module 23, a switch hook 24, a rectifier module 25, an earphone externally connected to a port E, and an microphone externally connected to a port M.
According to the standard of GB-T15279, in on-hook state, the switch hook 24 of telephone set 2 is in open state, the leak current in the telephone set shall be lower than 25 mA, and the feeding voltage outputted from the central office interface equipment 1 shall be 48V DC; in off-hook state, the switch hook 24 is in closed state, the DC resistance of the telephone set is lower than 350Ω, and the power consumption of the telephone set is about 18-60 mA in normal operating state. After the power supply and monitor module 12 judges that the telephone set is in off-hook and active state by detecting the feeding current, on one hand, it will send the active state via a port W to other modules at the office side for further treatment; on the other side, it will adjust its output voltage to about 10V. The power supply and monitor module 12 that supports remote billing indication also has a function of swapping feeding voltage polarity, i.e., it can swap the positive/negative polarity of feeding voltage outputted through the twisted pair line 3 according to the signal indication from a power feeding control port J after the session connection is established.
A ringing generator module 13 is arranged in the central office interface equipment 1 has, and a ringing module 23 is provided on the telephone set 2. To inform the called telephone subscriber of an incoming call, the ringing generator module 13 generates AC voltage with approximate 90V, 25 Hz from the input voltage VR, outputs the voltage via transformers 14 and 15 to the twisted pair line 3 connected to the telephone set, and then applies the voltage to the ringing module 23 in the telephone set 2 through the twisted pair line 3, so as to drive the ringing module 23 to ring up. The ringing generator module 13 generates ringing voltage in an intermittent manner, i.e., working for is and pausing for 4 s. In the is period when the ringing generator module 13 outputs ringing voltage, the feeding voltage output and the feeding current detection of the power supply and monitoring module 12 are disabled; in the 4 s period when the ringing generator module 13 pauses ringing voltage output, the feeding voltage output and the feeding current detection of the power supply and monitoring module 12 are enabled.
When the telephone subscriber picks up the phone, the switch hook 24 will be closed manually, and more circuit modules in the telephone set 2 will begin to work and consume electric current, resulting in greatly increased feeding current flowing through the twisted pair line 3 connected to the telephone set; thus, the power supply and monitoring module 12 can judge that the telephone set 2 is in off-hook and active state by detecting the feeding current.
The above waking up method used in simulation telephone system requires a separate ringing generator unit; in addition, there is a confliction between the simulation telephone system and the current detection system of on/off-hook state, and the structure of the system is very complex. Moreover, the 90V AC ringing approach results in high power consumption and high cost, which do not meet the demand for energy conservation and environmental protection; therefore, that approach should be abandoned.
In today's information age, ordinary telephone sets are gradually substituted by digital subscriber line (DSL) modems. People expect DSL modems can operate with remote power supply from the office side, similar to the ordinary telephone sets; when there is no data to transmit, the modem should enter into sleep state in which it almost consumes no power; when there is data to transmit locally, the modem should actively start up into operating state; when the modem is called by other network devices, it should be waken up into operating state by the central office equipment.
However, the waking-up and calling approach of ordinary telephone sets is only suitable for manual operation, but is not suitable for DSL modem's operate mode. For a telephone line connected with a plurality of devices, manual control can ensure only one unit is in online state, while a DSL modem cannot. If two units actively start up into operating state at the same time on a telephone line, or they start up into operating state because they receive calling signals at the same time, usually the DSL modem cannot establish a normal connection.
At present, other remote waking-up techniques disclosed in the art are related to remote waking-up computers. These waking-up methods require that the computer is equipped with a chassis power that can supply additional sleep power, and a motherboard and a network card that support remote waking-up. Actually, all the chassis power, motherboard, and network card are in live working state; the operating current drops greatly only because the parts that consume high power are shut down, which is to say, the computer is not in true power-off state entirely without consuming power.
In addition, some devices in homes or office locations also require remote waking-up for power supply, such as cameras and smart light fixtures that operate intermittently. At present, these devices have to be started up manually or always kept in ON state, and cannot realize remote waking up.
The present invention intends to solve or alleviate one of the problems described above.